The general goal of the current Program Project, "Neurobiology of Cerebellar-Brainstem System" (NS13742), continues to be that of further understanding of the functional basis for those cerebellar-brainstem interactions that are ultimately responsible for the organization of coordinated movement. The proposed research ranges from the study of ionic channels to the investigation of behavior and mathematical modeling. The Program Project will be concerned with four areas of neurobiological research: the functional properties of the neuronal elements in cerebellar circuits and their modulation by motor cortex activation; the morphological interaction leading to optimization of the climbing fibers and Purkinje cell system during development; the neuronal basis of motor learning and memory in brainstem and cerebellar circuits; and the modular organization of the cerebellum in relation to eye movement control. More specifically, we aim to characterize the physiological and morphological properties of neurons and neuronal Circuits relating to cerebellar and brainstem structures and to the sensory (vestibular, visual and proprioceptive) and motor (oculomotor, and vibrissae) interactions occurring within these bounds. Rather than employing a technique-oriented approach, over the years we have developed a range of expertise, from single-channel recording in single cells, voltage-dependent dye imaging, two photon laser-scanning microscopy, to multiple-unit recording in vivo. Our philosophy continues to be the study of these areas both in their own right as well as in the context of general CNS function.